An external deployable store, such as a bomb, is usually supported below an aircraft with an ejection system. The ejection system includes a pair of suspension hooks that engage the lugs on the top side of the store. When the store is to be released, the suspension hooks are operated to disengage the lugs so that the store may fall away from the aircraft. The suspension hooks are usually released by the firing of a pyrotechnic device activated by an electrical current. The resulting gases formed by the explosion of the pyrotechnic device create enough force to rotate the hooks free of the lugs and release the store.
The use of only a hook-and-lug arrangement was workable for some of the early types of slowly flying aircraft. The force of gravity was sufficient to allow the store to fall away from the aircraft smoothly after release. For more modern, faster aircraft, the air flow on the underside of the aircraft may interfere with the smooth, controllable dropping of the store away from the aircraft after it is released.
To ensure that the store is reliably separated from the aircraft, ejectors are provided to push the store away from the aircraft after the hooks are released from the lugs. The ejector must be powered by a power source that provides a controllable, rapidly applied force against the top side of the store in the correct sequence relative to the release of the lugs from the suspension hooks.
There are several other considerations for the store-ejection power source. The power source must be as light in weight and as compact as possible to avoid interference with the aircraft's aerodynamics. The power source should desirably be usable for multiple ejections of different stores, and should recycle rapidly after one ejection to be ready for the next ejection. The power source must consistently provide enough force to release the store without having to reload between firings. The ejection system should automatically regenerate and prime itself for the next application, thus eliminating the need for manual installation of a fresh power source. This feature is particularly desirable in the event of a hung store that requires several attempts to accomplish the release and ejection.
A number of different types of power sources for the ejectors have been used over the years. The most widely used method is the pyrotechnic device. This pyrotechnic device is ignited to generate a gas that expands and applies a force not only to rotate the hooks away from the lugs, but also to activate a piston that pushes the store away from the aircraft. This entire process occurs within a matter of seconds and is precision tuned to ensure that the hooks open before the piston is activated in an attempt to avoid catastrophic failure. While this method has proven effective, there are several disadvantages. One drawback is that each power source allows for only one release or ejection. The power source must then be reloaded manually before the next ejection. This inability to utilize the power source for multiple ejections not only creases added cost and down time, but it is also a safety hazard. Occasionally, stores become caught or “hung” on the hooks after the power source has been used. The pilot must then initiate a series of maneuvers designed to release the load. This becomes a risk because of the lack of control over when or where the store is released. In addition, the combustion product of the pyrotechnic device does not burn cleanly, resulting in an extremely corrosive, sticky by-product. In order to minimize the damage done by the corrosion and to lessen the risk of malfunction due to the sticky by-product, the ejection devices must be cleaned at the end of every firing day. While these pyrotechnic devices are generally reliable, there is still the risk of unintentional detonations. There have been occasions when a static electrical discharge from clothing was sufficient to set off the device before it could be loaded into the ejector, resulting in an injury.
A number of other power sources for ejection mechanisms have been proposed, but most are relatively complex or require too much space to be utilized effectively. These other power sources are also too heavy for many applications, and also may affect the aerodynamics of the aircraft.
There is a need for an improved store ejection system that is operable with fast recycling of the ejection process, is safe, is light in weight, is compact, and does not produce corrosive reaction products. The present invention fulfills this need, and further provides related advantages.